A polymerase chain reaction test - also known as a PCR test - is mainly carried out on those who have symptoms of Covid-19.
However, a multitude of countries are now requiring proof of a negative PCR for those arriving from the UK.
But what are PCR tests and how long do results take?
Here’s what you need to know.
What is a PCR test?
A PCR test is performed to detect genetic material from a specific organism, such as a virus, and detects the presence of a virus if you are infected at the time of the test.
A PCR test for Covid is a test used to diagnose people who are currently infected with SARS-CoV-2, which is the coronavirus that causes Covid-19.
The test involves taking a swab of the inside of your nose and the back of your throat, using a long cotton bud.
PCR tests - which are mainly for people with Covid symptoms - are sent to a lab to be checked, and differ from rapid lateral flow tests, which are only for people who do not have symptoms and give a quick result using a device similar to a pregnancy test.
If you have any of these three Covid symptoms, even if mild, you should get a PCR test as soon as possible:
- a high temperature
- a new, continuous cough
- you’ve lost your sense of smell or taste or it’s changed
You can order an NHS PCR test kit to be sent to your home or book an appointment at a walk-in or drive-through test site.
If you do the test at a test site, they will send the swab to the lab.
If you do the test at home, you must do the following before you do the test:
If you're posting a home test kit, you should only post it in a Royal Mail priority postbox. Do not take it to a Post Office or post it in a non-priority postbox.
However, you cannot use this service to book tests for travel. Private PCR tests must instead be taken for those who need tests for travel purposes.
If you are taking a PCR test for travel then a number of different companies offer these on a private basis either at a centre or at home.
If you are taking the test at home you will need to check with each company to see how to send the test back or if they offer a courier service.
How long do PCR results take?
Most people get their NHS PCR result the next day, but it may take up to three days.
You will usually get a text or email with your result when it's ready. If you use the NHS Covid-19 app, you may also get your result in the app.
If you do not get your results by day six, then call 119. Calls to 119 are free from a landline or mobile phone. Lines are open from 7am to 11pm.
If you are taking a private PCR test then costs vary and although most results are generally returned within 48-72 hours from the time the sample is received by the lab, this cannot always be guaranteed.
Before you travel, check foreign travel advice to find out whether the country or territory you want to go to will allow people from the UK to enter, and if you will need to show proof of vaccination or a negative Covid test to enter, or quarantine when you arrive.
Most countries that are asking for proof of a negative PCR test on arrival from the UK are requiring this to be taken within a 72-hour period, so you should also check this requirement before travelling to your destination.